Notes:
The LM3911 requires only a few resistors and capacitors to turn it into a full-function temperature controller. The schematic diagram illustrates
the simplicity of the overal circuit. The resistor network consisting of R1, R2, and R3 are used to provide the set point voltage for the feedback
input of the LM3911.

Resistor R4 limits the current through the internal voltage refernc3 of the LM3911 and can be selected for a wide range of values. 7K5 (7500 ohms)
is specified in the application notes of the device.

Resistor R5 pulls the output of the IC high when the temperature is below the set point. The internal resistor is in series with a diode that
allows a switching voltage of up to 35V to be used with the device. Electrolytic capacitor C2 will absorb any spikes at the output (like a fan).